Square Enix has released two extremely thick books including everything relating to Final Fantasy XIII inside them. Scans from the Scenario and Battle Ultimania are beginning to appear on the internet and with them some very interesting artwork and test footage of the game from before E3 2006.

The screenshots are actually from the Playstation 2 version of the game and it looks like they went in two completely different artistic directions before both of them were scrapped. The characters used in the screenshots are Yuna and Rikku heavily stylized and wearing completely different outfits. You can also see how the battle UI resembles what was used in the final game but with additions such as MP. See the screenshots below.



Source: FFSky